Cathode ray tube



Sept. 27, 1938. M. KNOLL CATHODE RAY TUBE Filed Aug. 4, 1934 .A Mw B theattached schematic drawing.

Patented Sept. 27, 1938 VCATHODE RAY TUBE" Knoll, Berlin, Germany,assignor to Telefunken Gesellschaft fiir Drahtlose Telegraphic m. b. H.,Berlin, Germany a Germany, a corporation of Application August 4, 1934,Serial No. 738.435

' In Germany August 1," 1933 i I 5 Claims.

Cathode-rays" which, for instance, are produced in a Braun tube which isto be adapted to the reception of television pictures, in order that ahighly luminous picture may be created, must be as dense or numerous asfeasible, while they should have as little hardness as possible in orderthat the necessary deflection potentials may not be unduly high. 1 I

To fulfill these two'requirements, according to the invention, thecathode-rays'are accelerated after their emergence from the cathode bythe agency of electrodes whose diameter is large in contrast with thecross-section of the cathode-ray pencil, whereupon they are retarded inwhich state of low velocity they are subjected to deflection, whereuponthey are again accelerated. Unless the focussing or concentration of thecathode-rays is accomplished simultaneously by the same electrodes whichserve to insure the first acceleration or the retardation, also thefocussing is to be efiected by additional electrodes of large diameter.

One exemplified embodiment of the invention shall be described in whatfollows by reference to Referring to the drawing, I0 denotes thecathode, II a disk serving to homogenize the first accelerator fieldwhich, for instance, may be in conductive relationship with the cathode.l2, l3, and I4 denote annular electrodes to which is applied a potentialthat is positive in reference to the cathode Ill, to be more precise,the potential applied to electrode [3 is more positive than that atelectrode I2. The

potential of the electrode I4 is negative relative to that of electrodel3 so that the cathode-rays which travel through the middle of electrodel3 at a fairly high rate of velocity, experience a decrease in speed.Between the electrodes 14 and I5, of which the last-named one surroundsthe deflector plates of the Braun tube, is applied the voltage of anauxiliary battery l6 whereby the electrode I5 is maintained at anegative potential relative to the electrode l4 and the next electrodel'l located below the deflector plates. As they enter electrode. l5 thecathode-rays are caused to pass through the equipotential surfacesindicated by the broken lines, said surfaces acting in the sense ofincreased convergence of the cathoderay pencil. The cathode-rays whichin this stage have a still lower speed than at the time they emergedfrom electrode M, will be deflected in the deflector plates even by theaction of small fields. On leaving electrode IS the cathode-rays arepassed again through curbed equipotential surfaces which are likewiseshown in the drawing by dotted lines and which, similarly as in the caseof f the equipotential surfaces traversed upon the exit fromtheelectrode l 5, tend toact in the sense of increased convergence ofthe pencil of"c'athode= rays. -Impressed upon the electrodes'l8-2l inthe lower end of the tube being of truncated con'e shape areincreasingly more positive potentials so that'thepotential of electrode[8 is more positive than that of electrode ll, thepotential at electrode19 more positive than that-of electrode l8, and so on. The potentialsacting at electrodes ll 2l are so graduated that the equipotentialsurfaces are practically spherical, with the center of the curvaturebeing located between the pairs of deflector plates. Hence, theequipotential surfaces are traversed by the pencil of cathode-raysalmost at right angles so that an increase in luminosity, but noadditional deflection of the spot upon the screen of the tube will becaused.

It will thus be evident that in a tube of the kind here disclosedcathode-rays in copious quantitles will be produced because of thepositive potential prevailing at the electrodes l2 and I3; furthermore,that these rays, on the one hand, because of the negative potential ofelectrode M in reference to electrode l3, and, on the other hand,because of the negative potential of the electrode [5 in reference toelectrode 14, will have between the deflecting plates but a moderatehardness so that they are readily deflectible, and that, finally, thespot upon the screen of the tube will turn out very bright for reason ofthe increasing positive potential between the electrodes, I1 and 2 I.

Instead of distinct electrodes "-2 l also a spiral made from resistormaterial through which an auxiliary current is conducted, could beemployed.

Similarly, electrodes l2l3 could be replacedby r a resistor spiraltraversed by an auxiliary current.

In the said spirals each individual turn or the fall of potentialoccurring along an individual turn can be compared with the voltagebetween two consecutive electrodes. A spiral with n. many turns wouldthen correspond to n many electrodes. In other words, the requisitefields are producible in just as fine a graduation by the use,

rescent screens of the kind used in connection with the recording ofsound-films and the like for the photographic recording of acousticactions, Roentgen-ray tubes, electron tubes used for amplification,rectification, and wavegeneration, and finally ion-ray tubes for thegeneration of high potential by kinetic ways and means where similarproblems are involved which are solvable by a similar application of theinvention.

I claim:

1. An electronic device comprising a fluorescent screen structure, anelectron emitting surface for producing an electron beam, a planeapertured shielding electrode lying in the plane of the electronemitting surface, a plurality of beam deflecting electrodes, and aplurality of hollow cylindrical electrodes positioned intermediate thedeflecting electrodes and the electron emitting surface, and a secondplurality of hollow cylindrical electrodes positioned intermediate thedeflecting electrodes and the fluorescent screen.

2. An electrode system for a cathode ray tube which comprises aplurality-of similar annular cylindrical electrodes, a shieldingcylindrical annular electrode in register with the plurality of similarelectrodes, a plurality of deflecting electrodes positioned within theshielding electrode, and a plurality of annular conical electrodes inregister with the shielding electrode.

3. An electrode system for a cathode ray tube comprising a source ofelectrons, a shield electrode in register with said source of electrons,a plurality of similar annular electrodes in register with said sourceof electrons, a plurality of hollow surface-of-revolution electrodes inregister with said first plurality of electrodes, a hollow shieldingelectrode intermediate the first and second plurality of electrodes, anddeflecting electrodes positioned within the shielding 'electrode.

4. A cathode ray' .tube comprising an envelope having an end wall, afluorescent screen on said end-wall, a source of electrons positionedremotely from the end wall, a shield electrode in register with saidsource of electrons, a plurality of I similar annular electrodes inregister with said source of electrons, a plurality of hollowsurface-of-revolution electrodes in register with said first pluralityof electrodes, a hollow shielding electrode intermediate the first andsecond plurality of electrodes, and deflecting electrodes positionedwithin the shielding electrode.

5. 'A cathode ray tube comprising an envelope having an end-wall, afluorescent screen on said end-wall, a source of electrons positionedre-- motely from the end Wall, a shieldelectrodedn register with saidsource of electrons, a plurality of similar annular electrodes inregister'with said source of electrons, a plurality of dissimilar hollowconical electrodes, a hollow shielding electrode intermediate the firstand second plurality of electrodes, and deflecting electrodes positionedwithin the shielding electrode.

7 MAX KNOLL.

